Currently, the PUREX process has found practical use as a method for separating and recovering plutonium from nuclear spent fuels (SF). This method is a method which comprises dissolving SF substances in a nitric acid solution, separating uranium (VI) and plutonium (IV) from nuclear fission products by the solvent extraction method using an organic solvent containing tributyl phosphate (TBP), and then separating plutonium (IV) from uranium (VI).
Americium (III) and curium (III), on the other hand, have so far been handled as high-level wastes, rather than reprocessed and recycled as has been plutonium (IV). Available as a method for separating transuranics (TRU) including americium (III) and curium (III) from high-level waste liquors is a wet separation process such as the solvent extraction method using CMPO (carbamoylmethylphosphine oxide), DIDPA (diisodecylphosphoric acid), or the like.
Further available is a method targeting a solution of nuclear spent fuels from a power generating reactor, the method comprising separating and recovering only uranium (VI) in a first extraction stage; separating and recovering all of the remaining actinoids, namely, neptunium (V), plutonium (IV), americium (III) and curium (III), in a second extraction stage; separately denitrating the resulting two actinoid solutions, i.e., a uranium(VI)-containing solution and an actinoid-containing solution; converting them into highly soluble oxide solids; and storing the oxide solids for a subsequent demand (see Patent Document 1).
Patent Document 1: JP-A-2002-243890
Patent Document 2: JP-A-2005-214706